Generalized\nOptical Binding for Multiple Assemblies\nof Nanoparticles under Multiple Laser Beams

Optical forces enable noncontact manipulation of micro-\nand nanoscale\nobjects, offering diverse applications. When a laser beam irradiates\nmultiple nanoparticles in a solvent, it induces the formation of an\nordered array with a finite distance between particles due to optical\nbinding, which results from the optical force exerted by scattered\nlight. This scattered light extends beyond the irradiation area, facilitating\ninteractions between spatially separated nanoparticle assemblies under\nmultiple laser beams. However, the extension of optical binding in\nthis context remains underexplored. In this study, we propose a concept\nof generalized optical binding between particle assemblies using two\nfocal laser beams. Under carefully designed conditions, the scattered\nlight between assemblies leads the particles to stable positions and\nimpedes rotational dynamics driven by the circular polarization of\nthe lasers. We demonstrate the fusion and reordering of two hexagonal\nassemblies, offering a blueprint for creating on-demand particle arrays\nthrough laser beam manipulation.